Under normal conditions, which catecholamine is the majority in the adrenal medulla?

In the adrenal medulla, epinephrine is the predominant catecholamine produced and released under normal physiological conditions. The adrenal medulla functions as a part of the body's fight-or-flight response and is responsible for the secretion of catecholamines, which include epinephrine and norepinephrine. While both of these are crucial for preparing the body to respond to stress, epinephrine is secreted in larger quantities compared to norepinephrine. It has a more significant role in increasing heart rate, dilating air passages, and mobilizing energy stores during stress.

Dopamine, also a catecholamine, serves primarily as a neurotransmitter in the brain rather than a major hormone in the adrenal medulla. Tyrosine is an amino acid that serves as a precursor to the synthesis of catecholamines, but it is not a catecholamine itself. Thus, the majority of what is produced and secreted in the adrenal medulla during stress response is epinephrine, highlighting its importance in the body's acute stress response mechanism.